625 research outputs found
Chemical Oscillations out of Chemical Noise
The dynamics of one species chemical kinetics is studied. Chemical reactions
are modelled by means of continuous time Markov processes whose probability
distribution obeys a suitable master equation. A large deviation theory is
formally introduced, which allows developing a Hamiltonian dynamical system
able to describe the system dynamics. Using this technique we are able to show
that the intrinsic fluctuations, originated in the discrete character of the
reagents, may sustain oscillations and chaotic trajectories which are
impossible when these fluctuations are disregarded. An important point is that
oscillations and chaos appear in systems whose mean-field dynamics has too low
a dimensionality for showing such a behavior. In this sense these phenomena are
purely induced by noise, which does not limit itself to shifting a bifurcation
threshold. On the other hand, they are large deviations of a short transient
nature which typically only appear after long waiting times. We also discuss
the implications of our results in understanding extinction events in
population dynamics models expressed by means of stoichiometric relations
A study on the possible usefulness of detrended fluctuation analysis of the electroencephalogram background activity in Alzheimer's disease
Carex modesti (Cyperaceae), a new species from southern Tanzania
A new species of Carex (Cyperaceae), Carex modesti, is described from southern Tanzania. It grows
on stream sides and peat bogs at about 2750 m in the Kitulo Plateau. It is morphologically distinct from the similar
species C. vallis-rosetto by its creeping rhizomes, coriaceous leaves and solitary spikes arising in each node.
Carex modesti is included in Carex sect. Spirostachyae subsect. Elatae together with other Carex species from
the tropical African mountain
Carex modesti (Cyperaceae), a new species from southern Tanzania
A new species of Carex (Cyperaceae), Carex modesti, is described from southern Tanzania. It grows
on stream sides and peat bogs at about 2750 m in the Kitulo Plateau. It is morphologically distinct from the similar
species C. vallis-rosetto by its creeping rhizomes, coriaceous leaves and solitary spikes arising in each node.
Carex modesti is included in Carex sect. Spirostachyae subsect. Elatae together with other Carex species from
the tropical African mountain
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